Thames Tidal Barrier

Today we visited the very impressive tidal barriers in Woolwich.  We drove there rather than going by train because my left hip and knee have been making walking very painful and I feared that going by public transportation, while very possible, would involve too much walking. Fortunately, Larry was willing to humor me and drove.

The River Thames is very much a tidal river - rising and falling many feet each day.  It is subject to major flooding during storm surges from the Atlantic when weather conditions are unfavorable.  The barrier consist of multiple closeable gates strung in a line across the River Thames at Woolwich which is just east of Greenwich as you head out towards the Channel. 

It was built between 1978 and 1982 to provide a way of preventing London from getting flooded.  It is expected that they will be able to do that job through the current century.  The barrier is currently deployed about 30 times a year, including a monthly deployment just to check that it all works.

There is an interesting visitors center which describes the history of London, the history of the flooding and the construction of the barriers.

We wish we had known about the monthly testing - we would have gone on August 2nd when they deployed them.  Oh well.

Some additional technical details from Larry:

Between each of the stands you see in the picture, there is a 3,000 TON steel structure that sits on the bottom in normal conditions.  During periods of possible tide surges, (storms and certain sun/moon positions), these steel structures are raised to form a solid barrier to prevent the water flow into the River Thames.  The steel structures are much like a half cylinder laying in a concrete depression so that the flat side is up and parallel to the bottom, allowing ships to pass over.  When deployed, these half cylinders are “rolled up” 90 degrees by huge hydraulic pistons to be perpendicular to the water flow, thus forming a solid dam.  They had working models in the visitors center – very impressive !